/Engine/Source/Runtime/GeometryCore/Public/DynamicMesh/MeshNormals.h
Initialize the given triangles of NormalOverlay with per-vertex normals, ie single overlay element for each mesh vertex. Only the triangles included in the region are considered when calculating per-vertex normals.
static void InitializeOverlayRegionToPerVertexNormals ( [FDynamicMeshNormalOverlay](API\Runtime\GeometryCore\DynamicMesh\FDynamicMeshNormalOverlay) * NormalOverlay, const [TArray](API\Runtime\Core\Containers\TArray)< int32 > & Triangles )